This invention relates to a cover device typically used on the end of the exhaust stack of an internal combustion engine. More particularly this invention relates to improvements over the cover device described in U.S. Pat. Nos. 2,983,216 and 4,059,045 and in U.S. Patent application Ser. No. 967,990, filed Dec. 11, 1978, now U.S. Pat. No. 4,255,928, which are incorporated herein by reference.
The protective cover devices described in the aforementioned patents are designed to be pivotally mounted upon the upper ends of respective generally upright exhaust stacks of internal combustion engines maintained outdoors in order that the devices will cover the ends of the exhaust pipes when the engines are not operating to prevent entry of rain or debris into the stacks. When exhaust gases exert pressure in a stack pipe during operation of the engine, the cover is raised against gravity off the end of the pipe to permit the gases to escape. The movement of the cap between open and closed positions is a rocking movement about a pivot. The large inertia of a heavy cover member causes considerable shock on the bearing of the pivot structure upon impacts at open and closed positions of the cover as well as loud noise produced by such impacts. Consequently, durability of the pivot structure has required brazing of the cover support arm to a sintered metal bushing which is journaled on a bearing mounted on a pivot shaft, as more fully described in the aforementioned U.S. Pat. No. 4,059,045. In addition to being complex, this pivot assembly is difficult to repair or replace.
Solution to the problem with noisy impact at the open and closed positions of the cover had been solved by providing a plastic bumper member which receives the impacts by engagement of stops mounted on the pivotal support arm for the cover, as described in the aforementioned U.S. Patent application Ser. No. 967,990; however, such bumper members have required fabrication of a groove therein in order to secure mounting on a bracket for convenient removal and replacement of the plastic bumper member.